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 ### 08 — Portfolio construction
 | Claim | Expected status |
 |-------|-----------------|
-| TopkDropout beats stochastic-control OptimalStopControl on the ensemble signal | `PROVEN` — exp 13, 14 |
-| Stop-control constructions churn and bleed costs (cost drag ≈ −11.3pp) | `PROVEN` — exp 13 |
+| TopkDropout beats stochastic-control OptimalStopControl on the ensemble signal | `HYPOTHESIS` (idea: pre-clean-lake exp 13/14, not re-tested post-reset) |
+| Stop-control constructions churn and bleed costs (cost drag ≈ −11.3pp) | `HYPOTHESIS` (idea: pre-clean-lake exp 13; mechanism consistent with clean exp 26) |
+| The reference and live book are TopkDropout n_drop=1, equal weight × risk_degree | `PROVEN` — exp 26, round 3 |
 | Fractional-Kelly sizing (exp 15) is unverified | `HYPOTHESIS` — run never finished |
 
 ### 09 — Cost/turnover frontier
@@ -118,9 +119,10 @@ Each chapter opens with its claims. The inventory below is the working contract:
 ### 10 — Risk limits
 | Claim | Expected status |
 |-------|-----------------|
-| $5M liquidity floor improves net IR 0.81→0.98 and cuts drawdown 7.9%→5.4% | `PROVEN` — exp 18 (pre-clean-lake; see note in chapter) |
-| Size/concentration caps hurt by cutting deployed capital | `PROVEN` — exp 18 |
-| Entry/risk gates are no-ops when the signal is the bottleneck | `PROVEN` — exp 20 (R2/R3 byte-identical) |
+| $5M liquidity floor improves net IR 0.81→0.98 and cuts drawdown 7.9%→5.4% | `HYPOTHESIS` (idea: pre-clean-lake exp 18, not comparable post-reset) |
+| Size/concentration caps hurt by cutting deployed capital | `HYPOTHESIS` (idea: pre-clean-lake exp 18) |
+| Entry/risk gates are no-ops when the signal is the bottleneck | `HYPOTHESIS` (idea: pre-clean-lake exp 20) |
+| The risk-limit spec executes and does not break the funnel (liq floor dropped 8, 10→10→10→9) | `PROVEN` — round 3 |
 | Exp-18 numbers are not comparable to post-reset runs due to env non-determinism | `PROVEN` — exp 20 R0 note |
 
 ### 11 — Live execution and reconciliation
diff --git a/book/chapters/12-synthesis.md b/book/chapters/12-synthesis.md
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+# Chapter 12 — Synthesis: How Proved Truth Compounds
+
+Status: drafting. Claim inventory: see `README.md` ch. 12.
+
+This chapter is the scoreboard: what actually moved performance, what was refuted, and why the book's methodology — not any single experiment — is the durable product of the campaign.
+
+## The scoreboard
+
+Everything PROVEN below is on the clean lake (exp 21+) or a reconciled post-reset round; everything else is labeled what it is.
+
+| Lever | What moved | Status |
+|-------|-----------|--------|
+| **Data quality** (clean-lake reset) | The single largest event: invalidated all pre-reset results; the reference collapsed and was rebuilt (IC 0.0354→0.0019, then rebuilt to 0.0511) | `PROVEN` — exp 21→22–24 (EVIDENCE#010–013) |
+| **Cost/turnover relief** (n_drop 2→1) | The largest *positive* lever: net −3.21%→+2.13% on an identical signal (IR 0.21, MDD −7.69%) | `PROVEN` — exp 26 (EVIDENCE#015) |
+| **Feature pruning** (compact generic set) | The biggest series of wins were refutations: OU (exp 25), momentum (exp 29), GARCH (exp 31) all rejected; the compact set stands (RankIC 0.0663) | `PROVEN` — exp 24/25/29/31 (EVIDENCE#013/#014/#017/#019) |
+| **Ensemble & seed count** | Variance reduction, not new information; 2 seeds < 5 seeds (net −1.49% vs +2.13%) | `PROVEN` — exp 28 (EVIDENCE#016) |
+| **Risk limits** | Executed and non-interfering in round 3 (liquidity floor dropped 8, funnel 10→10→10→9); the floor-beats-caps A/B is pre-reset idea material | `PROVEN` (execution) / `HYPOTHESIS` (A/B) — round 3 + exp 18 |
+| **Portfolio construction** | TopkDropout beat stochastic-control on the pre-reset lake; never re-tested post-reset | `HYPOTHESIS` (idea) — exp 13/14 |
+| **Live execution** | Funnel held, slippage 4.54 bps, cost ~$45, turnover 0.74 — the first reconciled live number | `PROVEN` — round 3 (EVIDENCE#020) |
+
+## The pattern beneath the scoreboard
+
+Two positive levers (data quality, cost relief), one protective discipline (pruning, whose wins were negatives), one reinforcement (seed count). The pattern: **performance improved by removing lies, removing cost, and removing features — not by adding anything to the signal.** The only surviving clean-lake addition candidate is exp 30's M2 (Sharpe-drift feature), which the book keeps at HYPOTHESIS precisely because it improved one layer and degraded another in a single unreproduced run (ch. 07).
+
+The refuted runs were as valuable as the wins: exp 11, 13, 14, 20, 25, 29, 31 each stopped a wrong direction at the cost of a few runs `(PROVEN — refuted runs recorded in the ledger; REFERENCED — falsification as method)`. A campaign that counts its refutations as output is a campaign that spends its budget learning, not re-learning.
+
+## The methodology that made it compound
+
+None of the scoreboard above is usable without the machinery of ch. 00–02:
+
+1. **The execution trail** (targets→decisions→fills, reconcile) is the spine — it is what let the desk catch the clean-lake collapse and what turns the live round into evidence.
+2. **The clean-lake boundary** is the watermark — it is why exp 18's pretty risk numbers are hypotheses and exp 26's thin-but-real numbers are facts.
+3. **Isolation and pre-registration** make each verdict attributable (ch. 07).
+4. **The two-layer metrics ladder** (rank + portfolio, ch. 01) is why exp 30 is a hypothesis and not a claim.
+5. **Live beats backtest** (ch. 11) is the final gate — no metric in this book outranks a reconciled round.
+
+## What the book still does not know
+
+- Whether the 50-ETF panel generalizes — the widest open question `TODO(evidence-needed: out-of-panel universe)`.
+- Why the strongest single-feature signal (OU) degrades the model (the OU paradox, ch. 01).
+- Whether 5-day reversal trades standalone net of costs (ch. 01, ch. 07).
+- Whether M2 reproduces (ch. 07), whether the risk-limit A/B holds on clean data (ch. 10), and whether a second live round confirms the funnel and slippage under a different regime (ch. 11).
+
+## Closing
+
+This book's claims are deliberately thin: a RankIC near 0.066 on 50 names, an IR near 0.2 net, one reconciled live round. That thinness is the point. Every number in it can be re-derived from a recorded run or a re-opened round; every hypothesis is marked as one; every backtest is labeled a backtest. A quant-desk reader can act on the book's method even where its edge is small — and the book expects its own claims to be superseded as the next rounds and experiments land (living document, `AGENTS.md` rule 6).
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